Control apparatus for liquid fuel metering devices



July I, 1969 a. w. GODDARD ET AL 3,452,729

CONTROL APPARATUS FOR LIQUID FUEL METERING DEVICES Filed May 2, 1967 B v T? H 17 34 I 22 b Tr 23 r 24 [K O ZQCV/ 1 United States Patent US. Cl. 123-140 4 Claims ABSTRACT OF THE DISCLOSURE A control apparatus for a liquid fuel metering device for an internal combustion engine comprising a mechanism responsive to inlet manifold depression and wh ch transfers such response to a displaceable member WhlCh controls the fuel metering device. The magnitude of displacement of the member is controlled by an adjustable cam.

Background of invention This invention relates to control apparatus for meter ing devices in fuel supply systems for internal combustion our US. Patent No. 2,891,701. The body 10 has an inlet 11 which is intended in use to be connected to the inlet manifold of an engine with which the apparatus is to be used, with the inlet 11 communicating with a pressureresponsivemechanism which includes an interior chamber 12 bounded at one side by a diaphragm 13 and the movement of which is responsive to the inlet manifold depression. The diaphragm 13 is supported by a pair of springs 14, 15 of differing rating and of differing diameter, with the inner smaller spring 15 having one end acting against an adjustable stop 16 located within the body 10 and the other end acting against a sheet metal plate 17. The larger spring 14 acts at one end against the sheet metal plate 17 and at the other end against a support member 18 for the diaphragm 13. The arrangement is such that throughout the total permitted travel of the diaphragm 13, the spring pressures resisting collapse of the diaphragm, under the influence of falling depression in the inlet manifold of the engine, will differ in relation to the ratings of the two springs 14, 15. As the diaphragm 13 collapses, the two springs will collapse until the sheet metal plate 17 engages a further adjustable stop 19 which is coaxial with and secured in the stop 16,

engines and particularly though not exclusively to petrol injection systems.

In our US. Patent No. 2,891,701, there is described a form of control apparatus having a member arranged to control the stroke of a shuttle-type fuel metering device in accordance with the depression in the inlet manifold of an engine with which the apparatus is to be associated. The apparatus described in U.S. Patent No. 2,891,701 includes a cam and roller mechanism whereby the stroke control of the fuel metering device is achieved and there is also means whereby the response to inlet manifold depression can be modified in accordance with several factors, such as for example when it is desired to start the engine from cold and which operation requires the introduction of an increased amount of fuel.

Summary of invention An object of the present invention is to provide an alternative form of control apparatus for controlling the metering of fuel in accordance with inlet manifold depression which is simple and convenient.

According to the present invention there is provided control apparatus for a liquid fuel metering device, an internal combustion engine comprising pressure-respon sive means displaceable on change in inlet manifold depression, an arm associated with said pressure-responsive means and displaceable in accordance therewith, a displaceable member for effecting control of the fuel-metering device, to which the apparatus is adapted to be attached, a cam with which the arm co-operates to displace the member on movement of the arm by the pressureresponsive means, and means for adjustably positioning the cam in order to determine the magnitude of displacement of the member.

Description of drawing An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing which is a cross-sectional view of control apparatus constructed in accordance with this invention.

Detail description of invention The control apparatus comprises a body 10 which is adapted, in a manner not illustrated, to be secured to a shuttle-type liquid fuel metering device as described in whereupon no further compression of the spring 15 will take place and resistance to collapse of the diaphragm will be under the influence of the spring 14 only. The limit of collapse of the diaphragm 13 will be reached when a still further adjustable stop 20 within the stop 19 is engaged by an abutment 21 secured to the center of the diaphragm 13.

Further fall in depression will therefore have no effect upon the diaphragm 13 below the value at which the stop 20 and the abutment 21 engage.

Connected to the center of the diaphragm 13, at the opposite side thereof from the abutment 21, is an arm 22 carrying a multiple roller element 23 which comprises three rollers (only one being illustrated) disposed upon a common axle 24 secured between two spaced elements which together form the arm 22. The arm 22 together with the roller element 23 is moved longitudinally within a chamber 25 in the body 10 with changes in depression in the chamber 12 on the opposite side of the diaphragm 13, with the chamber 25 being open to atmosphere so that atmospheric pressure is exerted on that side of the diaphragm 13. Extending through a bearing 26 in the body 10 is a plunger 27, the outer end of which is adapted to engage a movable abutment for the shuttle-type liquid fuel metering device. The plunger 27 is urged, when the apparatus is at rest before the engine is started, outwardly of the body by a compression spring 28 and the inner end of the plunger is engaged by the roller element 23. During operation of the engine, however, the metering device provides a force tending to hold the plunger 27 against the roller element 23.

The path of travel of the plunger 27 extends transversely with respect to the longitudinal path of travel of the arm 22, and to impart such transverse movement to the roller element 23, as longitudinal movement of the arm 22 takes place, there is provided an adjustablypositioned cam 29 with which the roller element 23 engages. It will readily be apparent that movement of the arm 22 along an inclined effective cam surface 29a causes the transverse movement of the plunger 27.

Adjustment of the position of the cam 29, to vary the extent of transverse movement of the roller element 23 and thus of the plunger 27 with changing depression in the inlet manifold of the engine, is initially achieved with respect to a mounting plate 30 which is connected to the cam through a pair of screws 31, 32. These screws 31, 32 pass through respective slots in the cam 29 so that relative angular displacement between the cam 29 and the plate 30 can take place about an axis 33, with an adjusted osition beingmaintain'edby ti htening the screws 31" an The plate 30 together with the cam 29 are pivotable within the body about an axis 35 and the degree of pivotal movement can be controlled by means of an external adjustable limit screw 34.

An external lever (not shown) is connected to the plate 30 at the position indicated at 35, and this can be connected to a manual or automatic control device for use during cold starting conditions. A tension spring 36 acts between the body 10 and a lug 37 on the plate 30.

In use, changes in the depression exerted in the chamber 12 upon the diaphragm 13 transmit longitudinal movement to the arm 22 and to the roller element 23 which rides along the cam surface 29a to urge the plunger 27 outwardly. The angular position of the cam surface 29a with respect to the path of travel of the arm 22 determines the extent of movement of the plunger 27. Actuation of the manual or automatic external control can be used to pivot the cam 29 about the axis 35 and thus vary temporarily the position of the effective cam surface 29a to increase the quantity of fuel delivered to the engine by increasing the shuttle stroke for cold starting. The extent of over-fueling is at a maximum-value with the greatest degree of depression, that is the normal depressions which are recorded in engines under idling conditions.

The external adjusting screw 34 can be used to trim the apparatus in accordance with atmospheric and/or engine temperature conditions or other variables, and can include if desired, a capsule or other device for sensing pressure or temperature conditions within the engine or in the surrounding atmosphere.

What we claim is:

1. Control apparatus for a liquid fuel metering device for an internal combustion engine, comprising pressureresponsive means displaceable on change in inlet manifold depression, an arm operable associated with said pressure-responsive means and displaceable in accordance therewith, a displaceable member for effecting control of the fuel-metering device to which the apparatus is adapted to be attached, a cam roller means mounted on the arm and engaging both the displaceable member and cam operative to displace the member on movement of the arm by the pressure-responsive means, a backing memher on which said cam is mounted and relative to which it is adjustable between fixed positions for varying the magnitude of the displacement of the displaceable memher, and said cam and backing member being together pivotable for varying temporarily the position of the efiective cam surface for permitting an increase in the quantity of fuel delivered to the engine.

2. Apparatus as claimed in claim 1, within which the pressure responsive means includes a diaphragm which is displaceable on change of inlet manifold depression, the arm being connected to thediaphragm for movement therewith.

3. Apparatus as claimed in claim 1, in which adjustable means are provided for limiting the pivotal movement of the cam and backing member.

4. Apparatus as claimed in claim 1, in which the arm comprises a pair of spaced elements between which is mounted said roller means.

References Cited UNITED STATES PATENTS 2,082,334 l/l937 Harcourt 74-110 2,783,652 3/1957 Smith 741 10 2,884,791 5/ 1959 Enstrom 74-110 2,965,090 12/ 1960 de Claire. 3,020,776 2/ 1962 May et al. 3,051,139 8/1962 Thorner. 3,199,337 8/1965 Ginn.

WILLIAM L. FREEH, Primary Examiner.

US. Cl. X.R. 74-110; 92-140 

